The IUCN Red List of Threatened Species™ announced on Monday that the world’s mammals face an extinction crisis, with almost one in four at risk of disappearing forever. The paper summarizing this comprehensive assessment is published today in the esteemed journal Science.

The new study to assess the world’s mammals shows at least 1,141 of the 5,487 mammals on Earth are known to be threatened with extinction. At least 76 mammals have become extinct since 1500. But the results also show conservation can bring species back from the brink of extinction, with five percent of currently threatened mammals showing signs of recovery in the wild.

“The reality is that the number of threatened mammals could be as high as 36 percent,” says Jan Schipper, of Conservation International and lead author in the Science article. “This indicates that conservation action backed by research is a clear priority for the future, not only to improve the data so that we can evaluate threats to these poorly known species, but to investigate means to recover threatened species and populations.”

The project to assess the world’s mammals was conducted with help from more than 1,800 scientists from over 130 countries. It was made possible by the volunteer help of IUCN Species Survival Commission’s specialist groups and the collaborations between top institutions and universities, including Conservation International, Sapienza Università di Roma, Arizona State University, Texas A&M University, University of Virginia, and the Zoological Society of London.

The paper is titled "The Status of the World's Land and Marine Mammals: Diversity, Threat, and Knowledge".